How to use Magnifiers and Dissecting 

 Microscopes. It is generally admitted that the 

 intelligent use of a magnifier is a great aid in micro- 

 scopical Studies and while its use is a simple matter, 

 some words of advice may be of aid in obtaining better 

 results, or lead to doing work with more comfort. In 

 all work, whether with simple or compound micro- 

 scopes, it is a good plan to start out with the principle 

 not to use a greater magnifying power than is necessary 

 to accomplish the' results in view. 



It should be made a 

 habit at the outset to 

 keep both eyes open. 



Keep the eye com- 

 fortably near to the 

 upper surface of the 

 lens, as the angular 

 view or field is in- 

 creased, there is the 

 least spherical aberra- 

 tion, and the focal dis- 

 tance is the greatest. 

 This can be easily 

 Fig 24. tested by gradually in- 



creasing the distance 



between the eye and lens, when it will be found that 

 the lens must be brought nearer to the object. In 

 single lenses the spherical and chromatic aberrations 



